A power supply unit as disclosed in PTL 1 is mounted in, for example, an electric vehicle which is driven by use of an electric motor or a hybrid vehicle which is driven by use of an engine in combination with an electric motor as a drive source of the electric motor. This power supply unit includes a battery unit and a busbar module. The battery unit is made up of a plurality of batteries, of which each battery has a positive electrode at one end and a negative electrode at the other end. The batteries are arranged neatly into a pile in such a way that electrodes having different polarities are laid adjacent to each other. The busbar module is laid on an upper surface of the battery unit where the electrodes are provided. FIG. 8 is a top view of the related busbar module disclosed in PTL 1. FIG. 9 is an enlarged view of part of the busbar module shown in FIG. 8.
The busbar module 101 shown in FIG. 8 and the like includes a plurality of busbars 103 which connect the plurality of batteries of the battery unit, not shown, in series by connecting the electrodes of the batteries which are laid adjacent to each other, a plurality of terminals 104 which are connected individually to the busbars 103 for detecting a voltage of the batteries to which the busbars 103 connect, a plurality of electric wires 105 which are connected individually to the terminals 104 and a plate 106 which accommodates the plurality of busbars 103, the plurality of terminals 104 and the plurality of electric wires 105. In FIG. 8, the plurality of electric wires 105 are omitted from illustration. In addition, an arrow X denotes a direction in which the plurality of batteries 20 are arranged neatly into a pile.
The busbar 103 is made of a metallic plate and a pair of holes 103a are provided therein through which the electrodes, which have a cylindrical shape, are passed. A positive electrode is passed through one of the pair of holes 103a and a negative electrode is passed through the other of the holes 103a, whereby the busbar 103 connects the batteries which are arranged to lie adjacent to each other in such a way that their electrodes having different polarities are laid adjacent to each other. The terminal 104 includes a plate-shaped electrode connector 141 which is placed on the busbar 103 and which has a hole 141a through which the electrode which is passed through one of the holes 103a is passed and an electric wire connector 143 which is connected with one end of the electric wire 105. The electrode connector 141 and the electric wire connector 143 are formed integrally. The terminal 104 is connected to a voltage detection circuit, which will be described later, via the electric wire 105 so as to output potentials of the positive electrode and the negative electrode of the batteries which are connected together by the busbar 103 to the voltage detection circuit.
The plate 106 has, as an overall planar shape, a substantially rectangular shape which is substantially equal in shape and size to the upper surface of the battery unit on which the electrodes are provided. The plate 106 is laid on the upper surface of the battery unit. The plate 106 includes a plurality of primary plates 106A which are aligned in a straight line along the arrow X and a secondary plate 106B which is positioned at an end portion of the plurality of primary plates 106A. The plates 106A, 106B are connected together by the other ends of the plurality of electric wires 105 which are attached to the respective terminals 104 at the one end thereof being disposed from one primary plate 106A to the other plates 106A, 106B which are arranged adjacent to each other. Note that in FIG. 8, only one of the plurality of primary plates 106A is shown.
The primary plate 106A includes a plurality of primary accommodating portions 160 which each accommodate the busbar 103 and the terminal 104 which is connected to the busbar 103 and which are aligned along the direction in which the plurality of batteries are arranged neatly into a pile, that is, the direction indicated by the arrow X, a plurality of secondary accommodating portions 164 having a trough shape which are aligned on a straight line which is parallel to the direction indicated by the arrow X in which the plurality of primary accommodating portions 160 are aligned for accommodating the electric wires 105 which are attached to the respective terminals 104, a plurality of lid portions 167 which are connected individually to the secondary accommodating portions 164 via hinges so as to open or close opening portions of the secondary accommodating portions 164 and a plurality of tertiary accommodating portions 168 which each connect the primary accommodating portion 160 and the secondary accommodating portion 164 which are laid to face each other with a space provided therebetween and accommodate the electric wire connector 143 of the terminal 104 and the one end of the electric wire 105 to which the electric wire 143 is attached. The other end of the electric wire 105 which is accommodated in the tertiary accommodating portion 167 is bent at substantially 90 degrees so as to be accommodated in the secondary accommodating portion 164.
The secondary plate 106B includes a plurality of primary accommodating portions 160 which each accommodate the busbar 103 and the terminal 104 which is connected to the busbar 103 and which are aligned along the direction in which the plurality of batteries are arranged neatly into a pile, that is, the direction indicated by the arrow X, a plurality of secondary accommodating portions 164 having a trough shape which are aligned on a straight line which is parallel to the direction indicated by the arrow X in which the plurality of primary accommodating portions 160 are aligned for accommodating the electric wires 105 which are attached to the respective terminals 104, a plurality of lid portions 167 which are connected individually to the secondary accommodating portions 164 via hinges so as to open or close opening portions of the secondary accommodating portions 164, a plurality of tertiary accommodating portions 168 which each connect the primary accommodating portion 160 and the secondary accommodating portion 164 which are laid to face each other with a space provided therebetween and accommodate the electric wire connector 143 of the terminal 104 and the one end of the electric wire 105 to which the electric wire 143 is attached, and an electric wire fixing portion 107 which fixes the other ends of the electric wires 105 which are disposed at an end portion of the secondary plate 106B which lies on a side lying farther away from the primary plate 106A. Namely, the electric wire fixing portion 107 is provided at the end portion of the secondary plate 106B. The electric wire fixing portion 107 has a rod-like shape and is continued from the secondary accommodating portion 164. An adhesive tape is wound round outer circumferences of the electric wire fixing portion 107 and the plurality of electric wires 105 which are placed round the electric wire fixing portion 107, whereby the plurality of electric wires 105 are fixed to the electric wire fixing portion 107 that is the secondary plate 106B.